The "Date and Time" section of the manual is dated and in some cases incorrect, and now that POSIX.1-2024 is official now is a good time update it. I plan to post fixes to the mailing list and am creating this bug report to have a bug ID for the fixes.
Patch proposed here: https://sourceware.org/pipermail/libc-alpha/2024-June/157324.html
No comments, so I installed the patch as commit ee768a30fe9099972dad04c49972c2508a208b9b, with a minor improvement to an example in a followup commit 7c1ec1b7d0b476610c811b0babeab831e626c088. Closing the bug report. By the way, POSIX.1-2024 was published yesterday in PDF form, but it's not online yet. See <http://www.opengroup.org/austin/> (2024-06-14)